1. Field of the Invention
The present invention relates to a method and apparatus for performing a record on a recordable optical disc such as a CD-R (CD-Recordable), CD-RW (CD-ReWritable), etc., and also relates to an optical disc. More particularly, the present invention relates to an optical disc recording method, an optical disc recording apparatus, and an optical disc, in which an appropriate recording power of a light beam can be accurately obtained by a test record so as to perform an actual record with high quality.
The present application is based on Japanese Patent Application No. 2000-151248, which is incorporated herein by reference.
2. Description of the Related Art
As a method of performing a record on a constant linear velocity (CLV) recordable optical disc such as a CD-R or CD-RW, used is a high-speed recording system in which a record is performed at a linear velocity higher than a standard linear velocity (single speed, i.e., 1× speed).
In a constant linear velocity control record, the spindle rotation number is higher as the record is performed on a more inner peripheral side of an optical disc. In the case of 16× speed, for example, the spindle rotation number is 8,000 or more rpm. Therefore, the degree of self-excited vibration of a drive is large (particularly, in the case of an eccentric disc). When a record operation is to be performed on an optical disc, an OPC (Optimum Power Control: adjustment to the optimum recording power of a recording beam) is previously performed by a test record. Typically, a test record is performed in a PCA (Power Calibration Area) which is in the innermost peripheral portion of a disc. In the case of a high-speed record, therefore, the spindle rotation number in a test record is so high that the test record is made unstable by self-excited vibration of the drive and the OpC cannot be accurately performed. As a result, an actual record of high quality cannot be performed.
In the case of a high-speed record, in an actual record, the spindle rotation number is higher as the record is performed on a more inner peripheral portion of a disc, and hence pits are caused to be unstably formed, by self-excited vibration. When so-called on-the-fly writing in which writing is conducted directly from a CD-ROM drive to a CD-R (RW) drive without once forming an image file in a hard disc drive is to be performed at a high speed, a recording method may be employed in which a record is performed while the CD-ROM drive conducts a high-speed reproduction at a constant revolution number (CAV), and the CD-R (RW) drive conducts a high-speed record at a constant linear velocity. In this method, the linear velocity of the CD-ROM drive which is conducting CAV reproduction is about 16× speed in the inner peripheral side even when the linear velocity is about 32× speed in the outer peripheral side. In an operation of reproducing a peripheral side, therefore, the data transfer cannot overtake the writing operation and so-called buffer under-run occurs, thereby causing the writing operation to fail.
As a method of solving the problems in an actual record, a method has been proposed in which, as shown in FIG. 2, a record on a CD-R (RW) is performed by CAV in the inner peripheral side, and by CLV in the outer peripheral side. Specifically, at the innermost peripheral position of a program area, a CAV record is started at a rotation number corresponding to, for example, 12× speed. When the linear velocity at this rotation number reaches, for example, 16× speed, a CLV record is thereafter performed at 16× speed. In this way, the CAV record and the CLV record are switched over, so that the maximum rotation number is suppressed to restrain self-excited vibration, and an on-the-fly writing error is prevented from occurring.
In the method in which a record is performed with switching over the CAV record and the CLV record, the liner velocity is changed during the CAV record, and hence the optimum recording power of a recording laser beam is sequentially changed. In order to comply with this, for example, an OPC which is to be performed in the test record prior to the actual record is performed for each of the initial value of the linear velocity (the minimum linear velocity) and the final value of the linear velocity (the maximum linear velocity) in the CAV record, and the optimum recording powers respectively for the two linear velocities are obtained. In a record according to the present invention, in an area where the CAV record is performed, a recording power of each position is obtained by, in accordance with the linear velocity at the position, interpolating optimum recording powers which have been obtained with respect to the initial value of the linear velocity and the final value of the linear velocity, and controlled to the interpolated value, and, in an the area where the CLV record is performed, the record is performed while maintaining the optimum recording power at the final value of the linear velocity in the CAV record. As described above, in the method in which a record is performed with switching over the CAV record and the CLV record, when an OPC is performed in the PCA area which is in the innermost peripheral portion of a disc, the OPC at the final value of the linear velocity must be performed at a high revolution number, so that the meaning of performing the CAV record in the inner peripheral side to suppress the maximum rotation number is lost.